A flooded/non-flooded condition of a flexible riser is an important indicator used in the determination of integrity of the riser. Flooded risers tend to deteriorate and fail more quickly due to the presents of sea water in the armor wires of the riser then non-flooded risers do. Thus, flexible riser inspections are needed and performed for flooded/non-flooded riser annulus. These inspections are used as part of the life assessment data for integrity of the flexible riser. Current methodology for inspecting risers under pressure is flawed, resulting in false positive inspections. These inspections may be carried out using subsea automated ultrasonic testing (AUT) with the intent of determining a flooded/non-flooded condition of the risers.
Current methodology also is premised on a premise that ultrasonic testing (UT) will only couple through internal layers of the flexible riser if the annulus of the riser is flooded. Therefore, if the riser annulus is flooded an ultrasonic measurement of the riser should reveal the internal makeup (layers) of the riser up to at least the first layer of armor wires. This type of inspection of risers under pressure is highly inaccurate, in part because below 750 meters water depth risers with a dry annulus will couple sound energy and appear as wet risers using the that methodology.